 /*******************************************************************************
  * Copyright (c) 2005, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.operations;

 import org.eclipse.core.commands.ExecutionException;
 import org.eclipse.core.commands.operations.IOperationHistory;
 import org.eclipse.core.commands.operations.IUndoContext;
 import org.eclipse.core.commands.operations.IUndoableOperation;
 import org.eclipse.core.commands.operations.LinearUndoViolationDetector;
 import org.eclipse.core.runtime.IAdaptable;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.jface.dialogs.MessageDialog;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.ui.IWorkbenchPart;
 import org.eclipse.ui.IWorkbenchPart2;
 import org.eclipse.ui.internal.Workbench;
 import org.eclipse.ui.internal.WorkbenchMessages;

 /**
  * <p>
  * An operation approver that prompts the user to see if linear undo violations
  * are permitted. A linear undo violation is detected when an operation being
  * undone or redone shares an undo context with another operation appearing more
  * recently in the history.
  * </p>
  * <p>
  * This class may be instantiated by clients.
  * </p>
  *
  * @since 3.1
  */
 public final class LinearUndoViolationUserApprover extends
         LinearUndoViolationDetector {

     private IWorkbenchPart part;

     private IUndoContext context;

     /**
      * Create a LinearUndoViolationUserApprover associated with the specified
      * workbench part.
      *
      * @param context
      * the undo context with the linear undo violation
      * @param part
      * the part that should be used for prompting the user
      */
     public LinearUndoViolationUserApprover(IUndoContext context,
             IWorkbenchPart part) {
         super();
         this.part = part;
         this.context = context;
     }

     /*
      * (non-Javadoc)
      *
      * @see org.eclipse.core.commands.operations.LinearUndoViolationDetector#allowLinearRedoViolation(org.eclipse.core.commands.operations.IUndoableOperation,
      * org.eclipse.core.commands.operations.IUndoContext,
      * org.eclipse.core.commands.operations.IOperationHistory,
      * org.eclipse.core.runtime.IAdaptable)
      */
     protected IStatus allowLinearRedoViolation(IUndoableOperation operation,
             IUndoContext context, IOperationHistory history, IAdaptable uiInfo) {

         if (this.context != context) {
             return Status.OK_STATUS;
         }

         final String message = NLS.bind(
                 WorkbenchMessages.Operations_linearRedoViolation,
                 getTitle(part), operation.getLabel());
         final boolean [] proceed = new boolean[1];
         Workbench.getInstance().getDisplay().syncExec(new Runnable () {
             public void run() {
                 // Show a dialog.
 part.setFocus();
                 proceed[0] = MessageDialog.openQuestion(part.getSite()
                         .getShell(), getTitle(part), message);
             }
         });

         if (proceed[0]) {
             // redo the local changes first
 while (operation != history.getRedoOperation(context)) {
                 try {
                     IStatus status = history.redo(context, null, uiInfo);
                     if (!status.isOK()) {
                         // flush the redo history because the operation
 // failed
 history.dispose(context, false, true, false);
                         return Status.CANCEL_STATUS;
                     }
                 } catch (ExecutionException e) {
                     // flush the redo history here because it failed.
 history.dispose(context, false, true, false);
                     return Status.CANCEL_STATUS;
                 }
             }
             return Status.OK_STATUS;
         }

         return Status.CANCEL_STATUS;
     }

     /*
      * (non-Javadoc)
      *
      * @see org.eclipse.core.commands.operations.LinearUndoViolationDetector#allowLinearUndoViolation(org.eclipse.core.commands.operations.IUndoableOperation,
      * org.eclipse.core.commands.operations.IUndoContext,
      * org.eclipse.core.commands.operations.IOperationHistory,
      * org.eclipse.core.runtime.IAdaptable)
      */
     protected IStatus allowLinearUndoViolation(IUndoableOperation operation,
             IUndoContext context, IOperationHistory history, IAdaptable uiInfo) {

         if (this.context != context) {
             return Status.OK_STATUS;
         }

         final String message = NLS.bind(
                 WorkbenchMessages.Operations_linearUndoViolation,
                 getTitle(part), operation.getLabel());
         final boolean [] proceed = new boolean[1];
         Workbench.getInstance().getDisplay().syncExec(new Runnable () {
             public void run() {
                 // Show a dialog.
 part.setFocus();
                 proceed[0] = MessageDialog.openQuestion(part.getSite()
                         .getShell(), getTitle(part), message);
             }
         });

         if (proceed[0]) {
             // redo the local changes first
 while (operation != history.getUndoOperation(context)) {
                 try {
                     IStatus status = history.undo(context, null, uiInfo);
                     if (!status.isOK()) {
                         // flush the operation history because the operation
 // failed.
 history.dispose(context, true, false, false);
                         return Status.CANCEL_STATUS;
                     }
                 } catch (ExecutionException e) {
                     // flush the undo history here because something went wrong.
 history.dispose(context, true, false, false);
                     return Status.CANCEL_STATUS;
                 }
             }
             return Status.OK_STATUS;
         }
         return Status.CANCEL_STATUS;
     }

     /*
      * Get the title for the specified part. Use the newer interface
      * IWorkbenchPart2 if available.
      */
     private String getTitle(IWorkbenchPart part) {
         String title;
         if (part instanceof IWorkbenchPart2) {
             title = ((IWorkbenchPart2) part).getPartName();
         } else {
             title = part.getTitle();
         }
         // Null title is unexpected, but use an empty string if encountered.
 if (title == null) {
             title = ""; //$NON-NLS-1$
 }
         return title;
     }
 }

